/*
 * Copyright (c) 2007 innoSysTec (R) GmbH, Germany. All rights reserved.
 * Original author: Edmund Wagner
 * Creation date: 30.05.2007
 *
 * Source: $HeadURL$
 * Last changed: $LastChangedDate$
 * 
 * the unrar licence applies to all junrar source and binary distributions 
 * you are not allowed to use this source to re-create the RAR compression algorithm
 * 
 * Here some html entities which can be used for escaping javadoc tags:
 * "&":  "&#038;" or "&amp;"
 * "<":  "&#060;" or "&lt;"
 * ">":  "&#062;" or "&gt;"
 * "@":  "&#064;" 
 */
package com.github.junrar.io;

import java.io.EOFException;
import java.io.IOException;

/**
 * A File like access to a byte array. (seek and read certain number of bytes)
 * 
 * @author $LastChangedBy$
 * @version $LastChangedRevision$
 */
public class ReadOnlyAccessByteArray implements IReadOnlyAccess {

	private int positionInFile;
	private byte[] file;

	/**
	 * Initialize with byte[ ]
	 * 
	 * @param file
	 *            the file given as byte array
	 */
	public ReadOnlyAccessByteArray(byte[] file) {
		if (file == null) {
			throw new NullPointerException("file must not be null!!");
		}
		this.file = file;
		this.positionInFile = 0;
	}

	@Override
	public long getPosition() throws IOException {
		return positionInFile;
	}

	@Override
	public void setPosition(long pos) throws IOException {
		if (pos < file.length && pos >= 0) {
			this.positionInFile = (int) pos;
		} else {
			throw new EOFException();
		}
	}

	/** Read a single byte of data. */
	@Override
	public int read() throws IOException {
		return file[positionInFile++];
	}

	/**
	 * Read up to <tt>count</tt> bytes to the specified buffer.
	 */
	@Override
	public int read(byte[] buffer, int off, int count) throws IOException {
		int read = Math.min(count, file.length - positionInFile);
		System.arraycopy(file, positionInFile, buffer, off, read);
		positionInFile += read;
		return read;
	}

	@Override
	public int readFully(byte[] buffer, int count) throws IOException {
		if (buffer == null) {
			throw new NullPointerException("buffer must not be null");
		}
		if (count == 0) {
			throw new IllegalArgumentException("cannot read 0 bytes ;-)");
		}
		int read = Math.min(count, file.length - positionInFile - 1);
		System.arraycopy(file, positionInFile, buffer, 0, read);
		positionInFile += read;
		return read;
	}

	@Override
	public void close() throws IOException {
	}
}
